Interlocking dual filter

ABSTRACT

An interlocking dual filter includes a first filter element having a filter media enclosed by a frame and a sealing gasket disposed around the frame. The frame of the first filter element has a depending flange which defines a space for receiving a second filter element having a different filter media. The flange includes a plurality of recesses which form a first latching arrangement. The first recesses are aligned with latching tabs which extend laterally from the frame of the second filter element so that when the second filter element is placed within the frame, the second filter element latches with the first filter element. In accordance with one embodiment, the filter media of the first and second filter elements are different so that the filter assembly may be customized to accommodate various air stream conditions and utilizations.

FIELD OF THE INVENTION

The present invention relates to air filters, and more particularly, thepresent invention relates to air filters which have more than onefiltering element.

BACKGROUND OF THE INVENTION

Air filters are used almost universally for internal combustion enginespowering automotive vehicles and land based equipment where airbornedust occurs. The amount and type of dust varies from one geographicallocation to another, so that air filters which may be effective in onelocation are not necessarily as effective in another location.

Air filters are also increasingly used for many applications other thaninternal combustion engines to filter from air streams particulatematter such as dust, pollen, mold spores, carbon particles,microorganisms and many other forms of particulate matter as well asodor-causing agents. Filtering needs differ from one location to anotherand differ at different areas of the world. Accordingly, there is a needto customize filter media according to the contaminants being removed.

With air filters for any purpose, some contaminants are trapped bydifferent filter materials and may clog those materials prior to othermaterials being clogged. In addition, there is a need to be able tocustomize the filter configurations according to customer orders.

Historically, in order to combine filter media of different types, mediawere co-pleated with one another. Co-pleating causes increasedrestriction which interrupts air flow. In addition, the capacity andefficiency of a filter may be reduced because one filter media cannot beconveniently separated from another. As knowledge accumulates as to thenatures of particulate contaminants in environmental air, filter mediaspecifically configured to trap selected particles are increasinglyavailable. Accordingly, there needs to be a more flexible arrangementfor configuring air filters so as to take advantage of this knowledge.

SUMMARY OF THE INVENTION

It is a feature of the present invention to provide new and improved airfilter assemblies, wherein a plurality of filter elements are providedto achieve flexibility so that the filter of a selected geometric sizeand shape may have customized characteristics.

In view of this feature and other features, the present invention isdirected to an air filter assembly comprising a first filter element andsecond filter element, wherein the filter elements have upstream anddownstream sides and include first and second filter media,respectively, which are mounted in first and second filter frames,respectively. The first filter frame has a first latching arrangement onits downstream side and the second filter element has a second latchingarrangement on its upstream side for coupling with the first latchingarrangement on the downstream side of the first filter. A peripheralseal for sealing with a housing is arranged around only the first filterelement.

In accordance with a further aspect of the invention, the first andsecond filter elements have selected sizes and shapes. Wherein theshapes are the same and the size of the first filter element is slightlylarger than that of the second filter element.

In accordance with another aspect of the invention, the first latchingarrangement on the downstream side of the first filter element comprisesa projecting flange having lacking apertures, while the second latchingarrangement on the upstream side of the second filter element compriseslatching tabs for receipt in the latching apertures.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other features and attendant advantages of the present inventionwill be more fully appreciated as the same becomes better understoodwhen considered in conjunction with the accompanying drawings, in whichlike reference characters designate the same or similar parts throughoutthe several views, and wherein:

FIG. 1 is a front face view of a filter of the type utilizing theprinciples of the present invention;

FIG. 2 is an end view, partially in section, taken along lines 2--2 ofFIG. 1, showing a filter assembly in accordance with the presentinvention;

FIG. 3 is an exploded end view, partially in section, showing first andsecond filter elements comprising the filter assembly of FIG. 2;

FIG. 4 is an end view, partially in section, of a second embodiment ofthe invention, also taken along lines 2--2 of FIG. 1; and

FIG. 5 is an exploded end view, partially in section, of the filterelements shown in FIG. 4.

DETAILED DESCRIPTION

Referring now to FIG. 1, there is shown a filter assembly 10 configuredin accordance with the principles of the present invention, wherein thefilter assembly 10 has a specific shape and specific dimensions in orderto fit within a specific housing 12. The specific housing 12 is shown indotted lines and can accept filter assemblies 10 of variouscharacteristics. In order to fit within or to cover the opening of thehousing 12, the filter assembly 10 is rectangular with a specific width(w) and a specific length. The housing 12 may, for example, be a housingin the air intake of an internal combustion engine (not shown).

Generally, the filter assembly 10 comprises a rectangular filter media14, a relatively stiff rectangular frame 16 made of plastic and arectangular gasket 18 to seal with the housing 12.

Referring now to FIG. 2, it is seen that the filter assembly 10 iscomprised of a first filter element 20 and a second filter element 22.The first filter element 20 has the top view of FIG. 1, because itcompletely covers the second filter element 22. Together, the filters 20and 22 remove particulate material from an airstream 23 which firstimpacts an upstream face 25 of the first filter element 20, exits from adownstream face 26 of the first filter element, enters through theupstream face 27 of the second filter element 22, and exits the filterelement 22 through downstream face 28. The second filter element 22 hasa width and length less than that of the first filter element, but alsohas a rectangular shape. The gasket 18 around the frame 16 is onlymounted on the first filter element 20, the second filter element 22being gasketless and relying on the gasket 18 for sealing purposes.

Referring now to FIG. 3, it is seen that the first filter element 20 andsecond filter element 22 are separable so that different combinations offilter elements may be used for different environments. The frame 16 ofthe first filter element has a dependent flange or skirt 34 which formsan enclosure 35 that surrounds the juncture of the first and secondfilter elements 20 and 22 so that air flows substantially only from thefirst filter element through the second filter element. The flange orskirt 34 has a plurality of apertures 36 disposed in spaced relationtherearound which form female components of a first latchingarrangement. The second filter element 22 is received within theenclosure 35 and has a plurality of outwardly extending projections ortabs 37 which are aligned with the apertures 36 in the flange or skirt34 of the first filter element 20 to provide a male latchingarrangement. When the second filter element 22 is nested within thespace 35, the projections or tabs 37 couple or latch the elements 20 and22 together to form the filter assembly 10, the gasket 18 on the firstfilter assembly 20 sealing both filter elements with respect to thehousing 12 (shown in dotted lines in FIG. 1).

The second filter element 22 has a filter media 38 which preferably hasdifferent characteristics from the filter media 14 of the first filterelement 20. The specific characteristics of the filter media 38 dependon the condition of the air which is being filtered and the use to whichthe air is put. For example, the filter media 38 might be the primaryfilter media and the filter media 14 of the first filter element 20could be a prefilter. Both the filter media 14 and the filter media 38could be pleated cellulose or synthetic material, or the filter media 14could be a mat of non-pleated filter media, such as spun-bondedpolyester. There are a number of combinations which can be accomplishedby configuring the assembly 10 in different ways.

Between the first filter element 20 and the second filter element 22,there is a space 40. The space 40 is available for a thin air treatingmaterial which may be, for example, a sheet or thin panel 42 (shown indotted lines in FIG. 3) of activated carbon for removing odoriferouscompounds or substances from the air stream 23.

Referring now to FIG. 4, there is shown a second embodiment of theassembly, wherein the filter assembly is designated by the numeral 50and includes a polyurethane gasket 52 which is disposed at the upstreamface 53 of a first filter element 54. The polyurethane gasket 52 is usedto seal the assembly 50 with the housing 12 (FIG. 1) and has a lip 56which overlies the upstream face 53 of a first filter media 57. Adepending peripheral portion 59 of the gasket 52 overlies the outsidesurface of a frame 60 of hard plastic that surrounds the filter media57.

The second filter element 70 is substantially similar to the secondfilter element 22 of FIGS. 1-3, but includes a polyurethane seal 72which is received within a channel 74 formed in a frame 76 adjacent theupstream face 78 of a second filter media 80. The polyurethane seal 52around the first filter element 54 prevents air from bypassing thesecond filter media 80 of the second filter element 70. As with thefirst embodiment of the invention, it is preferable that the frames 60and 76 of the second embodiment be formed by injection molding.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

What is claimed is:
 1. An air filter assembly for mounting in a housing,wherein the air filter assembly comprises:a first filter element panelfor filtering particles, the first filter element panel having anupstream side and a downstream side and including a first filter mediamounted in a first filter frame, the first filter frame having a firstlatching arrangement proximate a downstream side thereof; a secondfilter element panel for filtering particles, the second filter elementpanel having an upstream side and a downstream side and including asecond filter media mounted in a second filter frame, the second filterframe having a second latching arrangement at an upstream side thereoffor coupling with the first latching arrangement on the downstream sideof the first filter, and a peripheral flange around the juncture of thefirst and second filter element wherein the air is constrained to flowsubstantially only from the first filter element through the secondfilter element.
 2. The air filter assembly of claim 1, further includinga peripheral seal for sealing with the housing, the peripheral sealbeing arranged around only the first filter element.
 3. The air filterassembly of claim 2, wherein at least one of the filter media is apleated filter media.
 4. The filter arrangement of claim 3, wherein oneof the filter media is a mat of non-pleated fiber material and thesecond filter media is a pleated cellulose filter media.
 5. The filterassembly of claim 1, wherein the first filter media and second filtermedia are both pleated filter media made of cellulose or syntheticmaterial.
 6. The air filter assembly of claim 1, wherein there is aspace between the downstream side of the first filter element andupstream side of the second filter element and wherein a relatively thinsheet of air treatment material is disposed in the space.
 7. The airfilter assembly of claim 6, wherein the relatively thin sheet ofmaterial comprises activated carbon.
 8. The air filter assembly of claim1, wherein the first latching arrangement comprises a skirt defining anenclosure proximate the downstream side of the first filter element, theskirt having a shape corresponding to the shape of the second filterelement and including a plurality of spaced apertures therein and thesecond latching arrangement comprising a plurality of projecting tabs onthe frame of the second latching element, the tabs being received in theapertures in the skirt to latch the second filter element to the firstfilter element so as to configure the assembly.
 9. The filter assemblyof claim 8, wherein the first and second filter elements have selectedsizes and shapes, wherein the shapes are the same and the size of thefirst filter element is slightly larger than the size of the secondfilter element, wherein the second filter element is received within theenclosure of the first filter element.
 10. The air filter assembly ofclaim 8, wherein the second filter element includes a sealing gasketdisposed around the periphery of the upstream face thereof for sealingwith the downstream face of the first filter element.
 11. The filterassembly of claim 1, wherein the first and second frames are injectionmolded from plastic material.